Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device and a manufacturing method thereof are provided for the improvement of the reliability of copper damascene wiring in which a film between wiring layers and a film between via layers are comprised of an SiOC film with low dielectric constant. A film between wiring layers, a film between wiring layers, and a film between via layers are respectively comprised of an SiOC film, and stopper insulating films and a cap insulating film are comprised of a laminated film of an SiCN film A and an SiC film B. By doing so, it becomes possible to reduce the leakage current of the film between wiring layers, the film between wiring layers, and the film between via layers, and also possible to improve the adhesion of the film between wiring layers, the film between wiring layers, and the film between via layers to the stopper insulating films and the cap insulating film.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a technique for manufacturing asemiconductor device. More particularly, the present invention relatesto a technique effectively applied to a wiring structure formed by theso-called damascene process and to a semiconductor device with such awiring structure.

BACKGROUND OF THE INVENTION

In order to suppress the wiring delay caused by the scaling down of thesemiconductor device, the attempts to reduce the wiring resistance andthe wiring capacitance have been made. With respect to the wiringresistance, the measures by means of design technique and the adoptionof the wiring made of copper to be a main conductor layer have beenexamined. For the formation of the copper wiring, the so-calleddamascene process is employed, in which metal for the wiring such ascopper to be the main conductor layer is deposited on a substrate and onthe surface of the trenches formed in an insulating film and then thesuperfluous metal outside the trenches is removed by the CMP (ChemicalMechanical Polishing) method, thus forming the wiring patterns in thetrenches.

Meanwhile, with respect to the wiring capacitance, the adoption of thelow dielectric constant material with the relatively low relativedielectric constant of about 2 to 3 has been examined. Above all, thefilm made of silicon-oxycarbite (referred to as SiOC, hereinafter) whichis excellent in mechanical strength is considered as a promising lowdielectric constant material.

Note that Japanese Patent Laid-Open No. 2001-326279 (Patent Document 1)discloses the technique, in which the insulating film that comes intocontact with the copper wiring of the multilayered insulating filmconstituting the interlayer insulating film is formed by plasmanizingthe film forming gas containing the alkyl compound having the siloxanebond and any one oxygen-containing gas of N₂O, H₂O, and CO₂, whose flowrate is equal to or less than the flow rate of the alkyl compound, andthen reacting them mutually.

Also, Japanese Patent Laid-Open No. 2001-110789 (Patent Document 2)discloses the method of depositing and etching the intermetallicdielectric layer comprised of the first dielectric layer containingsilicon, oxygen, and about 5% of carbon by atomic weight and the seconddielectric layer containing silicon, oxygen, and about two-thirds orless of the carbon contained in the first dielectric layer.

Also, Japanese Patent Laid-Open No. 2002-203899 (Patent Document 3)discloses the technique for improving the adhesion between theinterlayer insulating film and the barrier film by forming theinterlayer insulating film with an SiO film, an SiOF film or an SiOCfilm and by forming the copper barrier film with an SiC film.

Also, Japanese Patent Laid-Open No. 2002-134494 (Patent Document 4)discloses the technique for preventing the crosstalk by forming theinterlayer insulating film with an SiOC film, an SiOF film, or a CF filmand forming the polishing stopper film for the CMP (Chemical MechanicalPolishing) and the copper barrier film with an SiC film.

Also, Japanese Patent Laid-Open No. 2002-353310 (Patent Document 5)discloses the technique for improving the etching of the vias by formingthe interlayer insulating film with an SiOC film and forming the copperbarrier film with an SiC film or an SiN film.

Also, Japanese Patent Laid-Open No. 2003-142593 (Patent Document 6)discloses the technique for forming an MIM (Metal Insulator Metal)capacitor by forming the interlayer insulating film with an SiO film, anSiOF film, or an SiOC film and forming the copper barrier film with anSiC film or an SiN film.

Also, Japanese Patent Laid-Open No 2003-152076 (Patent Document 7)discloses the technique for improving the dielectric breakdownresistance of the wiring by forming the interlayer insulating film withan SiOC film, an SiOF film, a BF film, or a CF film, forming thepolishing stopper film for the CMP with an SiC film, an SiN film, an SiOfilm, or an SiON film, and forming the copper barrier film with an SiOCfilm or an SiON film.

Also, Japanese Patent Laid-Open No. 2000-200832 (Patent Document 8)discloses the technique for improving the adhesion of the copper barrierfilm by forming the interlayer insulating film with an SiO film, an SiOFfilm, or an SiN film and forming the copper barrier film with an SiCfilm or an SiN film.

Also, Japanese Patent Laid-Open No. 2002-9150 (Patent Document 9)discloses the technique for preventing the aggregation of copper wiringby forming the copper diffusion preventing film of the copper damascenewiring to have a laminated structure of the first insulating filmcomprised of an SiN film, an SiC film, or an SiCN film and the secondinsulating film comprised of an SiN film.

Also, Japanese Patent Laid-Open No. 2002-373936 (Patent Document 10)discloses the technique in which an SiC film, an SiN film, an SiCN film,or an SiON film is used as the etching stopper film when forming thecopper damascene wiring.

Also, Japanese Patent Laid-Open No. 2002-170882 (Patent Document 11) andJapanese Patent Laid-Open No. 2002-270691 (Patent Document 12) disclosethe technique in which, in the process for forming the copper damascenewiring, after performing the CMP for filling copper into the trenches inthe insulating film, the surface treatment of exposing the coppersurface to the plasma of ammonia (NH₃) or helium (He) is performed, andthen, a copper diffusion preventing film such as an SiC film, an SiNfilm, or an SiCN film is formed.

SUMMARY OF THE INVENTION

The inventors of the present invention have examined the manufacturingmethod of the damascene wiring. The technique examined by the inventorsof the prevent invention will be shown below, and the summary thereofwill be provided as follows.

First, a stopper insulating film and an insulating film for forming thewiring (referred to as film between wiring layers, hereinafter) aresequentially deposited. The film between wiring layers is comprised ofan SiOC film formed by the plasma CVD (Chemical Vapor Deposition)method, and the stopper insulating film is comprised of a silicon oxide(referred to as SiO, hereinafter) film, a silicon nitride (referred toas SiN, hereinafter) film, or a silicon carbonitride (referred to asSiCN, hereinafter) film formed by, for example, the plasma CVD method.The stopper insulating film functions as an etching stopper layer in theetching of the film between wiring layers.

Next, the wiring trenches are formed in the predetermined region of thefilm between wiring layers and the stopper insulating film by theetching with using the patterned photoresist film as a mask.Subsequently, a barrier film, for example, a titanium nitride film isformed on the entire surface of the substrate including the surface ofthe wiring trenches, and then, a copper film for filling the wiringtrenches is formed. The copper film functions as a main conductor layerand can be formed by, for example, the plating method. Thereafter, thecopper film and the barrier layer in the region outside the wiringtrenches are removed by the CMP method, thus forming the copper wiringin the wiring trenches.

Next, a cap insulating film functioning as a barrier layer is formed onthe copper wiring in order to prevent the diffusion of the copper fromthe copper wiring. The cap insulating film is comprised of, for example,an SiO film, an SiN film, or an SiCN film formed by the plasma-CVDmethod. In addition to the function as a barrier layer, the capinsulating film has a function as an etching stopper layer when formingconnection holes in the insulating film on the copper wiring.

However, as a result of the examination of the scaling down of thedamascene wiring with the process dimensions of 0.1 μm or smaller withthe increasing demand for the higher integration density, the problem asfollows has been found out. That is, when polishing the copper film bythe CMP method, the film between wiring layers, which is comprised of anSiOC film, and the stopper insulating film comprised of an SiO film, anSiN film or an SiCN film are separated from each other at the interfacetherebetween, and the manufacturing yield of the semiconductor devicehaving the damascene wiring is lowered.

An object of the present invention is to provide a technique capable ofimproving the reliability of the damascene wiring in which an SiOC filmis used to form the insulating film in which the wiring trenches areformed or the insulating film in which the connection holes are formed.

The above and other objects and novel characteristics of the presentinvention will be apparent from the description and the accompanyingdrawings of this specification.

The typical ones of the inventions disclosed in this application will bebriefly described as follows.

The present invention provides an semiconductor device in which metalwiring is formed in the trenches formed in an interlayer insulating filmon a semiconductor substrate and a cap insulating film for preventingthe diffusion of the metal which constitutes the wiring is formed overthe interlayer insulating film and the metal wiring, wherein theinterlayer insulating film is comprised of an SiOC film, an SiC filmformed on the SiOC film, and an SiON film formed on the SiC film, andthe cap insulating film is comprised of an SiCN film and an SiC filmformed on the SiCN film.

The present invention provides the method of manufacturing asemiconductor device having the damascene wiring, wherein an insulatingfilm in which the wiring trenches are formed and an insulating film inwhich the connection holes are formed are comprised of an SiOC film, andan SiC film with a thickness of 5 nm or larger is deposited so as to bein contact with the SiOC film.

The effect obtained by the typical ones of the inventions disclosed inthis application will be briefly described as follows.

In the damascene wiring in which an SiOC film is used to form aninsulating film in which the wiring trenches are formed and aninsulating film in which the connection holes are formed, an SiC film isused to form the stopper insulating film and the cap insulating film,alternatively, a laminated structure comprised of an SICN film, an SiOCfilm, and an SiC film interposed between the SiCN film and the SiOC filmis used to form the stopper insulating film and the cap insulating film.By doing so, it is possible to prevent the separation of the SiOC film.In this manner, it is possible to improve the reliability of thedamascene wiring.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a sectional view showing the principal part of a semiconductorsubstrate which illustrates the manufacturing method of the CMOSFETaccording to the first embodiment of the present invention;

FIG. 2 is a sectional view showing the principal part of thesemiconductor substrate which illustrates the manufacturing method ofthe CMOSFET according to the first embodiment of the present invention;

FIG. 3 is a sectional view showing the principal part of thesemiconductor substrate which illustrates the manufacturing method ofthe CMOSFET according to the first embodiment of the present invention;

FIG. 4 is a sectional view showing the principal part of thesemiconductor substrate which illustrates the manufacturing method ofthe CMOSFET according to the first embodiment of the present invention;

FIG. 5 is a sectional view showing the principal part of thesemiconductor substrate which illustrates the manufacturing method ofthe CMOSFET according to the first embodiment of the present invention;

FIG. 6 is a sectional view showing the principal part of thesemiconductor substrate which illustrates the manufacturing method ofthe CMOSFET according to the first embodiment of the present invention;

FIG. 7 is a sectional view showing the principal part of thesemiconductor substrate which illustrates the manufacturing method ofthe CMOSFET according to the first embodiment of the present invention;

FIG. 8 is a sectional view showing the principal part of a semiconductorsubstrate which illustrates the manufacturing method of the CMOSFETaccording to the second embodiment of the present invention;

FIG. 9 is a graph showing the measurement results of the leakage currentcharacteristics of the insulating films (SiC film, SIGN film, and SiNfilm);

FIG. 10 is a sectional view showing the principal part of asemiconductor substrate which illustrates the CMOSFET according to thefourth embodiment of the present invention;

FIG. 11 is a graph showing the measurement results of the TDDBcharacteristics of the insulating films (SiC film, SiCN film, and SiNfilm);

FIG. 12 is a graph showing the evaluation of the relationship betweenthe stress migration characteristics of the copper wiring and each ofthe SiCN film and the SiC film;

FIG. 13 is a sectional view showing the principal part of asemiconductor substrate which illustrates the CMOSFET according to thefifth embodiment of the present invention;

FIG. 14 is a sectional view showing the principal part of asemiconductor substrate which illustrates the CMOSFET according to thesixth embodiment of the present invention; and

FIG. 15 is a sectional view showing the principal part of asemiconductor substrate which illustrates the CMOSFET according to theseventh embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. Note that componentshaving the same function are denoted by the same reference symbolsthroughout the drawings for describing the embodiments, and therepetitive description thereof is omitted.

First Embodiment

The manufacturing method of the CMOSFET (Complementary Metal OxideSemiconductor Field Effect Transistor) according to the first embodimentof the present invention will be described along the manufacturingprocess with reference to the sectional views in FIGS. 1 to 7 showingthe principal part of the semiconductor substrate shown.

First, as shown in FIG. 1, a semiconductor substrate 1 made of, forexample, p⁻-single crystal silicon is prepared and device isolationregions 2 are formed on the main surface of the semiconductor substrate1. Next, an impurity is ion-implanted with using a patterned photoresistfilm as a mask to form a p-well 3 and an n-well 4. A p-type impuritysuch as boron is ion-implanted into the p-well 3, and an n-type impuritysuch as phosphorus is ion-implanted into the n-well 4. Thereafter, theimpurity for controlling the threshold of the MISFET (Metal InsulatorSemiconductor FET) can be ion-implanted into the respective wellregions.

Next, a silicon oxide film to be a gate insulating film 5, apolycrystalline silicon film to be a gate electrode 6, and a siliconoxide film to be a cap insulating film 7 are sequentially deposited toform a laminated film, and then, the laminated film is etched with usinga patterned photoresist film as a mask. In this manner, the gateinsulating films 5, gate electrodes 6, and the cap insulating films 7are formed.

Next, after depositing a silicon oxide film by, for example, the CVDmethod, sidewall spaces 8 are formed on the sidewalls of the gateelectrodes 6 by the anisotropic etching of this silicon oxide film.Thereafter, an n-type impurity such as phosphorus or arsenic ision-implanted into the p-well 3 with using a photoresist film as a maskto form the n-type semiconductor regions 9 on both sides of the gateelectrode 6 of the p-well 3. The n-type semiconductor regions 9 areformed in the self-alignment manner with respect to the gate electrode 6and the sidewall spacers 8 and function as the source/drain of then-channel MISFET. Similarly, a p-type impurity such as boron fluoride ision-implanted into the n-well 4 with using a photoresist film as a maskto form the p-type semiconductor regions 10 on both sides of the gateelectrode 6 of the n-well 4. The p-type semiconductor regions 10 areformed in the self-alignment manner with respect to the gate electrode 6and the sidewall spacers 8 and function as the source/drain of thep-channel MISFET.

Next, as shown in FIG. 2, after depositing a silicon oxide film on thesemiconductor substrate 1 by the sputtering method or the CVD method,the silicon oxide film is polished by the CMP method. By doing so, aninterlayer insulating film 11 having a flat surface is formed.Subsequently, connection holes 12 are formed in the interlayerinsulating film 11 by the etching with using a patterned photoresistfilm as a mask. The connection holes are formed at the requiredpositions, for example, on the n-type semiconductor regions 9 or on thep-type semiconductor regions 10.

Next, a titanium nitride film is formed on the entire surface of thesemiconductor substrate 1 including the surface of the connection holes12 by, for example, the CVD method, and then, a tungsten film to befilled into the connection holes 12 is formed by, for example, the CVDmethod. Thereafter, the tungsten film and the titanium nitride film inthe region other than in the connection holes 12 are removed by, forexample, the CMP method, thus forming the plugs 13 in the connectionholes 12.

Subsequently, a first wiring layer is formed by using the singledamascene process. First, a stopper insulating film 14 is formed on theplugs 13 and a film between wiring layers 15 is formed. Since the firstwiring layer described later is formed on the stopper insulating film 14and the film between wiring layers 15, the total thickness thereof isdetermined depending on the design thickness necessary to the firstwiring layer.

The stopper insulating film 14 is a film serving as an etching stopperin the process for forming the wiring trench in the film between wiringlayers 15 and is made of a material having the etching selectivity withrespect to the film between wiring layers 15. The stopper insulatingfilm 14 is comprised of a silicon carbide (referred to as SiC,hereinafter) film with nitrogen content of 1% or less, and its thicknesscan be, for example, about 5 nm or larger. The SiC film is formed by,for example, the plasma CVD method under the conditions as follows. Thatis, the rf power is 200 to 1000 W, the pressure is 2 to 10 Torr, thetemperature is 300 to 400° C., the gas seed is C containing gas (e.g.alkylsilane) and He, and the gas flow rate is 100 to 2000 sccm. The filmbetween wiring layers 15 is comprised of an SiOC film and has a relativedielectric constant of about 3. Also, the SiOC is formed under theconditions as follows. That is, the rf power is 200 to 1000 W, thepressure is 2 to 10 Torr, the temperature is 300 to 400° C., the gasseed is C containing gas (e.g. alkylsilane), He, and O₂, and the gasflow rate is 100 to 2000 sccm.

Note that the SiC film constituting the stopper insulating film 14 andthe SiOC film constituting the film between wiring layers 15 can beformed with one plasma CVD apparatus. For example, the following twomethods can be used: that is, the one in which the SiC film and the SiOCfilm are respectively formed in the two chambers provided in the plasmaCVD apparatus; and the one in which the SiC film and the SiOC film aresuccessively formed in the single chamber under different film formingconditions such as the gas to be used.

Subsequently, wiring trenches 16 are formed in the predetermined regionsof the stopper insulating film 14 and the film between wiring layers 15by the etching with using a patterned photoresist film as a mask.

Next, a barrier metal layer 17 is formed over the entire surface of thesemiconductor substrate 1 including the surfaces of the wiring trenches16. The barrier metal layer 17 is comprised of, for example, a tantalumfilm and has a thickness of about 50 nm on the flat surface of thesubstrate. The tantalum film is formed by, for example, the sputteringmethod. It is also possible to form the barrier metal layer 17 withtitanium nitride or tantalum nitride.

Subsequently, a seed layer of copper (not shown) is formed on thebarrier metal layer 17 by, for example, the CVD method or the sputteringmethod, and then, a copper film 18 is formed on the seed layer by theelectroplating method.

Next, as shown in FIG. 3, the copper film 18 and the seed layer arepolished by the CMP method. Thereafter, the barrier metal layer 17 onthe film between wiring layers 15 is removed by the further polishing.In this manner, the copper film 18 (including the seed layer) and thebarrier metal layer 17 in the region other than the wiring trenches 16are removed and the wiring 19 of the first wiring layer is formed.

Incidentally, in the technique examined by the inventors of thisinvention in which the stopper insulating film is comprised of an SiOfilm, an SiN film or an SiCN film and the film between wiring layers iscomprised of an SiOC film, the stopper insulating film and the filmbetween wiring layers are separated from each other at the interfacethereof in the CMP process of the copper film and the barrier layer.However, in the first embodiment in which the stopper insulating film 14is comprised of an SiC film and the film between wiring layers 15 iscomprised of an SiOC film, the stopper insulating film (SiC film) 14 andthe insulating film (SiOC film) 15 have been not separated from eachother at the interface thereof in the CMP process of the copper film(including the seed layer) and the barrier metal layer 17.

TABLE 1 SiOC SiC SiO SiCN SiN Young's Modulus (GPa) 18 63 112 133 221Stress (MPa) 47 62 −140 −245 −151 Nitrogen Content (%) <1 <1 4 20 45

The Young's modulus, stress, and nitrogen content of each insulatingfilm are shown in Table 1. The adhesion between the SiOC film and eachof the insulating films becomes smaller in the order of the SiN film,SiCN film, SiO film, and SiC film, and the adhesion to the SiOC filmtends to depend on the nitrogen content. Also, the Young's modulusbecomes smaller in the order of SiN film, SiCN film, SiO film, SiC film,and SiOC film. In addition, the SiOC film and the SiC film show thetensile stress, and on the other hand, the SiN film, the SiCN film, andthe SiO film show the compressive stress.

Judging from the above, it is thought that the molecular structureterminated by O and C enhances the bond between the molecules at theinterface to improve the adhesion at the interface of the SiOC film.Furthermore, if the SiC film which has the tensile stress similar to theSiOC film, the difference in Young's modulus from the SiOC film of 50GPa or less, and the difference in stress of 50 MPa or less is providedso as to come into contact with the SiOC film, the SiC film can relaxthe load in the horizontal and the vertical directions generated duringthe CMP process of the copper film, and thereby reducing the separationat the interface between the SiOC film and the SiC film.

Note that the case where an SiC film is used as the stopper insulatingfilm 14 has been exemplified here. However, it is also possible to formthe stopper insulating film 14 with other insulating film if it has thedifference in Young's modulus from the SiOC film of 50 GPa or less, orthe difference in stress of 50 MPa or less. Also, the case where the SiCfilm constituting the stopper insulating film 14 is formed by the plasmaCVD method and the film forming conditions have been exemplified here.However, the process and the film forming conditions are not limited tothose described here.

Next, a second wiring layer is formed by the dual damascene process.First, as shown in FIG. 4, a cap insulating film 20, an insulating filmin which connection holes are to be formed (referred to as film betweenvia layers, hereinafter) 21, and a stopper insulating film 22 forforming wiring are sequentially formed on the wiring 19 of the firstwiring layer.

The cap insulating film 20 is comprised of an SiC film with a nitrogencontent of 1% or less and a thickness of, for example, about 5 nm orlarger. In addition, the cap insulating film 20 has a function toprevent the diffusion of copper. Also, it is made of a material havingthe etching selectivity with respect to the film between via layers 21and is used as an etching stopper in the process for forming theconnection holes in the film between via layers 21. The SiC film isformed by, for example, the plasma CVD method, and the film formingconditions approximately equal to those of the SiC film constituting thestopper insulating film 14 can be used.

The film between via layers 21 is comprised of an SiOC film, the SiOCfilm is formed by, for example, the plasma CVD method, and the filmforming conditions approximately equal to those of the SiOC filmconstituting the film between wiring layers 15 can be used.

The stopper insulating film 22 is made of an insulating material havingthe etching selectivity with respect to a film between wiring layersdeposited later on the film between via layers 21 and the stopperinsulating film 22, and it is comprised of an SiC film with the nitrogencontent of 1% or less with a thickness of, for example, about 5 nm orlarger. The SiC film is formed by, for example, the plasma CVD method,and the film forming conditions approximately equal to those of the SiCfilm constituting the stopper insulating film 14 can be used.

Next, a photoresist film patterned into the hole shape is formed on thestopper insulating film 22, and the stopper insulating film 22 is etchedwith using the photoresist film as a mask.

Subsequently, a film between wiring layers 23 is formed on the stopperinsulating film 22. The film between wiring layers 23 is comprised of anSiOC film. The SiOC film is formed by, for example, the plasma CVDmethod, and the film forming conditions approximately equal to those ofthe SiOC film constituting the film between wiring layers 15 can beused. Note that, since wiring trenches to which the second wiring layerdescribed later is filled are formed in the stopper insulating film 22and the film between wiring layers 23, the total thickness thereof isdetermined depending on the design thickness necessary to the secondwiring layer.

Thereafter, as shown in FIG. 5, a photoresist film patterned into thetrench shape is formed on a film between wiring layers 23, and the filmbetween wiring layers 23 is etched with using the photoresist film as amask. In this case, the cap insulating film 22 functions as an etchingstopper film.

Subsequently, the film between via layers 21 is etched with using thephotoresist film and the stopper insulating film 22 as masks. In thiscase, the cap insulating film 20 functions as an etching stopper layer.

Subsequently, the exposed cap insulating film 20 is removed by, forexample, the dry etching method. Simultaneous with the removal of thecap insulating film 20, the stopper insulating film 22 is also removed.In this manner, the connection holes 24 are formed in the cap insulatingfilm 20 and the film between via layers 21, and the wiring trenches 25are formed in the stopper insulating film 22 and the film between wiringlayers 23.

Next, as shown in FIG. 6, a barrier metal layer 26 is formed over theentire surface of the semiconductor substrate 1 including the surfacesof the connection holes 24 and the wiring trenches 25. The barrier metallayer 26 is comprised of, for example, a tantalum film and has athickness of, for example, about 50 nm over the flat surface of thesubstrate. The tantalum film is formed by, for example, the sputteringmethod. It is also possible to form the barrier metal layer 26 withtitanium nitride and tantalum nitride.

Subsequently, a seed layer (not shown) of copper is formed on thebarrier metal layer 26 by, for example, the CVD method or the sputteringmethod, and a copper film 27 is formed on the seed layer by, forexample, electroplating method.

Next, as shown in FIG. 7, the copper film 27 and the seed layer arepolished by the CMP method. Thereafter, the barrier metal layer 26 onthe film between wiring layers 23 is removed by the further polishing.In this manner, the copper film 27 (including the seed layer) and thebarrier metal layer 26 in the region other than the wiring trenches 25are removed and the wiring 28 of the second wiring layer formed togetherwith the connection member is formed.

Also in the CMP process of this copper film 27 (including the seedlayer) and the barrier metal layer 26, similar to the CMP process of thecopper film 18 (including the seed layer) and the barrier metal layer17, no separation has been caused at the interface between the capinsulating film (SiC film) 20 and the film between via layers (SiOCfilm) 21, at the interface between the film between via layers (SiOCfilm) 21 and the stopper insulating film (SiC film) 22, and at theinterface between the stopper insulating film (SiC film) 22 and the filmbetween wiring layers (SiOC film) 23.

Subsequently, though not shown, a cap insulating film 29 is formed onthe wiring 28 of the second wiring layer, and after forming the wiringin the upper layer, the entire surface of the semiconductor substrate 1is coated with a passivation layer. In this manner, the CMOSFET isapproximately completed.

Note that, although the CMOSFET is exemplified as the semiconductordevice formed on the main surface of the semiconductor substrate 1 inthe first embodiment, the semiconductor device formed on the mainsurface of the semiconductor substrate is not limited to this.

Also, in the first embodiment, when forming the wiring 28 of the secondwiring layer by the dual damascene process, the hole patterns are formedin the stopper insulating film 22 in advance and then the connectionholes 24 in the film between via layers 21 and the wiring trenches 25 inthe film between wiring layers 23 are simultaneously formed with usingthe cap insulating film 20 and the stopper insulating film 22 as etchingstopper layers. However, the forming process is not limited to this. Forexample, the methods as follows are also available. That is: the methodin which the connection holes 24 are formed in the film between wiringlayers 23 and in the film between via layers 21 by the etching withusing the photoresist film patterned into the hole shape as a mask andthen the wiring trenches 24 are formed in the film between wiring layers23 by the etching with using the photoresist film patterned into thetrench shape as a mask; and the method in which the wiring trenches 25are formed in the film between wiring layers 23 by the etching withusing the photoresist film patterned into the trench shape as a mask andthen the connection holes 24 are formed in the film between via layers21 by the etching with using the photoresist film patterned into thehole shape as a mask.

As described above, according to the first embodiment, in which the filmbetween wiring layers 15, the film between wiring layers 23, and thefilm between via layers 21 are comprised of an SiOC film made of amaterial with a relatively low dielectric constant and the stopperinsulating films 14 and 22 and the cap insulating film 20 in contactwith the film between wiring layers 15, the film between wiring layers23 and the film between via layers 21 are comprised of an SiC film, itbecomes possible to prevent the separation at the interface between thefilm between wiring layers 15 and the stopper insulating film 14 duringthe CMP process for forming the wiring 19 of the first wiring layer andthe separation at the interface between the cap insulating film 20 andthe film between via layers 21, at the interface between the filmbetween via layers 21 and the stopper insulating film 22, and at theinterface between the stopper insulating film 22 and the film betweenwiring layers 23 during the CMP process for forming the wiring 20 of thesecond wiring layer.

Second Embodiment

The manufacturing method of the CMOSFET according to the secondembodiment of the present invention will be described with reference tothe sectional view in FIG. 8 showing the principal part of thesemiconductor substrate.

The case where the stopper insulating films 14 and 22 and the capinsulating film 20 are comprised of an SiC film has been described inthe first embodiment. However, in this second embodiment, the stopperinsulating films 14 and 22 and the cap insulating film 20 are comprisedof an SiCN film A and an SiC film B, in which the SiCN film A can reducethe leakage current in comparison to the SiC film, and the SiC film B isinterposed between the SiOC films constituting the film between wiringlayers 15, the film between wiring layers 23, and the film between vialayers 21 and the SiCN film A. The thickness of the SiCN film A is, forexample, about 40 nm, and the thickness of the SiC film B is, forexample, about 10 nm. Also, the nitrogen content of the SiCN film A is1% or larger.

Also, the SiCN film A is formed by, for example, the plasma CVD method,and the film forming conditions thereof are as follows. That is, the rfpower is 200 to 1000 W, the pressure is 2 to 10 Torr, the temperature is300 to 400° C., the gas seed is C containing gas (e.g. alkylsilane), HN3and He, and the gas flow rate is 100 to 2000 sccm. Also, the SiC film Bis formed by, for example, the plasma CVD method, and the film formingconditions thereof are as follows. That is, the rf power is 200 to 1000W, the pressure is 2 to 10 Torr, the temperature is 300 to 400° C., thegas seed is C containing gas (e.g. alkylsilane) and He, and the gas flowrate is 100 to 2000 sccm.

FIG. 9 is a graph showing the measurement results of the leakage currentcharacteristics of the three kinds of insulating films (SIC film, SiCNfilm, and SiN film) in which the horizontal axis represents the electricfield intensity (MV/cm) and the vertical axis represents the leakagecurrent of the films (A/cm²). As is evident from the graph, at theelectric field intensity of 3 MV/cm, the SiCN film shows the smallestleakage current and the SiC film shows the largest leakage current.

As described above, in the second embodiment, the stopper insulatingfilms 14 and 22 and the cap insulating film 20 are mainly comprised ofthe SiCN film A with relatively small leakage current and the SiC film Bis interposed between the SiOC film, which constitutes the film betweenwiring layers 15, the film between wiring layers 23, and the filmbetween via layers 21, and the SiCN film A. By doing so, it becomespossible to reduce the leakage current between the wirings and toprevent the separation of the SiOC film.

Third Embodiment

In the third embodiment, an SiOC film which contains nitrogen is used toconstitute the film between wiring layers 15, the film between wiringlayers 23, and the film between via layers 21, and an SiCN film withrelatively small leakage current is used to constitute the stopperinsulating films 14 and 22 and the cap insulating film 20. The SiOC filmwhich contains nitrogen is formed by, for example, the plasma CVDmethod, and the film forming conditions thereof are as follows. That is,the rf power is 200 to 1000 W, the pressure is 2 to 10 Torr, thetemperature is 300 to 400° C., the gas seed is C containing gas (e.g.alkylsilane), O₂ and N₂, or C containing gas (e.g. alkylsilane) and N₂O,and the gas flow rate is 100 to 2000 sccm. Also, the SiCN film is formedby, for example, the plasma CVD method, and the film forming conditionsthereof are as follows. That is, the rf power is 200 to 1000 W, thepressure is 2 to 10 Torr, the temperature is 300 to 400° C., the gasseed is C containing gas (e.g. alkylsilane), NH₃ and He, and the gasflow rate is 100 to 2000 sccm. The thickness of the SiCN film is, forexample, about 50 nm.

As described above, according to the third embodiment, the adhesiontherebetween can be improved by containing nitrogen in the SiOC film. Inthis manner, it is possible to reduce the leakage current between thewirings and simultaneously to prevent the separation of the SiOC film.

Fourth Embodiment

As shown in FIG. 10, in the fourth embodiment, the stopper insulatingfilms 14 and 22 and the cap insulating film 20 are respectively formedof the laminated film of the SiCN film A and the SiC film B.

FIG. 11 is a graph showing the measurement results of TDDB(Time-dependent dielectric breakdown) characteristics of the three kindsof insulating films (SiC film, SiCN film, and SiN film), in which thehorizontal axis represents the electric field intensity (MV/cm) and thevertical axis represents the TDDB lifetime (second). As is evident fromthe graph, the TDDB lifetime of the SiCN film is longer than that of theSiC film.

Meanwhile, FIG. 12 is a graph showing the evaluation of the relationshipbetween the stress migration characteristics of the copper wiring (viaportion) and each of the SiCN film and the SiC film, in which thehorizontal axis represents the width of the copper wiring (μm) and thevertical axis represents the failure rate (%) of the wiring due to thestress migration. As is evident from the graph, when the width of thecopper wiring reaches a predetermined value or more, the stressmigration characteristics of the copper wiring is remarkablydeteriorated in the case of the SiCN film. On the other hand, the stressmigration characteristics of the copper wiring are hardly deterioratedin the case of the SiC film regardless of the width of the copperwiring. In addition, the laminated film of the SiCN film and the SiCfilm shows the intermediate characteristics of these films.

As described above, the stopper insulating films 14 and 22 and the capinsulating film 20 are comprised of the laminated film of the SiCN filmA and the SiC film B. By doing so, it becomes possible to prevent thedeterioration of the TDDB characteristics of the stopper insulatingfilms 14 and 22 and the cap insulating film 20 and also to reduce theleakage current. Furthermore, it is possible to prevent thedeterioration of the stress migration characteristics of the copperwiring.

Note that, in the case where the stopper insulating films 14 and 22 andthe cap insulating film 20 are respectively comprised of the laminatedfilm of the SiCN film A and the SiC film B, the adhesion at theinterface between the SiOC film, which constitutes the film betweenwiring layers 15, the film between wiring layers 23, and the filmbetween via layers 21, and the SiCN film A is reduced. For itsprevention, in this embodiment, the film between wiring layers 15, thefilm between wiring layers 23, and the film between via layers 21 arerespectively comprised of a three-layered structure of an SiOC film C,an SiC film B, and an SiON film D so as to avoid the direct contactbetween the SiOC film C and the SiCN film A. In this case, the thin SiCfilm B between the SiOC film C and the SiON film D is an adhesion layerfor improving the adhesion between the SiOC film C and the SiON film D.Also, in order to reduce the dielectric constant of the film betweenwiring layers 15, the film between wiring layers 23, and the filmbetween via layers 20 as much as possible, it is desirable that thethickness of the SiON film D having the dielectric constant higher thanthe SiOC film C is made smaller than that of the SiOC film C, and also,the nitrogen content thereof is set smaller than 5 atoms % or less. TheSiON film D is deposited by, for example, the plasma CVD method (formingtemperature=350 to 400° C.) with using monosilane (SiH₄) and nitrogenmonoxide (N₂O) as source gas.

Fifth Embodiment

In the case where the film between wiring layers 15, the film betweenwiring layers 23, and the film between via layers 21 are respectivelycomprised of the three-layered structure of an SiOC film C, an SiC filmB, and an SiON film D as described in the fourth embodiment, since theetching selectivity of the SiC film B serving as an adhesion layer isdifferent from that of the SiOC film C and the SiON film D, the SiC filmB functions as an etching stopper in the etching process for forming thewiring trenches 16 and 25 and the connection holes 24. Consequently, theproblem of reduction of the throughput occurs.

Therefore, in this embodiment, the film between wiring layers 15, thefilm between wiring layers 23, and the film between via layers 21 arerespectively comprised of a two-layered structure of an SiOC film C andan SiON film D as shown in FIG. 13 so as to prevent the reduction of thethroughput of the etching for forming the wiring trenches 16 and 25 andthe connection holes 24.

Meanwhile, in the case where the SiC film B serving as an adhesion layeris not provided, the adhesion at the interface between the SiOC film Cand the SiON film D is reduced, and the separation of the filmsfrequently occurs.

One of the causes of the film separation is that the stress at the roomtemperature after forming the SiOC film C is 45 MPa (tensile stress) butthe stress at 450° C. is −16 MPa (compressive stress), and thus, thefilm stress is changed from the tensile stress to the compressivestress, and the change amount thereof is large, that is, 61 MPa (45MPa−(−16 MPa)).

For its solution, the SiOC film C is deposited at high temperature (forexample, forming temperature of 375° C.). By doing so, the stress at theroom temperature after forming the SiOC film C becomes 53 MPa (tensilestress), and the stress at 450° C. becomes 78 MPa (tensile stress).Therefore, the SiOC film C in which the change in stress due to thetemperature change is small (the change amount is 25 MPa (78 MPa−53MPa)) is obtained, and thus, the adhesion to the SiON film D can beimproved. Also, after forming the SiOC film C, the helium (He) plasmaprocess or oxygen plasma process is performed to its surface, and then,the SiON film is deposited. By doing so, the adhesion therebetween canbe improved. Note that, in the case where the deposition temperature ofthe SiOC film C is too high and the plasma process is excessive, thedielectric constant of the SiOC film C is reduced. Therefore, it ispreferable that the deposition temperature is set to 400° C. or lowerand the plasma process time is set to 20 seconds or shorter (forexample, about 15 seconds).

In addition, when depositing the SiON film D on the SiOC film C, theratio of the monosilane and nitrogen monoxide serving as source gas ischanged to obtain the film with the diffraction ratio of 1.485 or lessand the nitrogen content of 3 to 4% or less. By doing so, the adhesionto the SiOC film C can be improved.

Sixth Embodiment

In the fifth embodiment, the film between wiring layers 15, the filmbetween wiring layers 23, and the film between via layers 21 arerespectively formed of the two-layered structure of the SiOC film C andthe SiON film D, and the various processes for improving the adhesiontherebetween are performed. In this embodiment, however, the filmbetween wiring layers 15, the film between wiring layers 23, and thefilm between via layers 21 are respectively formed of the two-layeredstructure of the SiOC film C and an SiOCN film E as shown in FIG. 14. Inthis case, since the composition of the SiOCN film E is close to that ofthe SiOC film C in comparison to the SiON film D and good adhesion canbe obtained, the various process for improving the adhesion between thefilms like those performed in the fifth embodiment is unnecessary.

The SiOCN film E can be deposited on the SiON film D by adding thenitrogen containing gas to the source gas in the middle of thedeposition of the SiON film D and then continuing the depositionprocess. Note that it is desirable that the nitrogen concentration inthe SiOCN film E is set to 10 atoms % or less in order to prevent theincrease of the dielectric constant.

In addition, though not shown, the film between wiring layers 15, thefilm between wiring layers 23, and the film between via layers 21 can beformed of the two-layered structure of the SiOCN film E and the SiONfilm D. Since the composition of the SiOCN film E is close to that ofthe SiON film D in comparison to the SiOC film C and good adhesion canbe obtained, the various process for improving the adhesion between thefilms like those performed in the fifth embodiment is unnecessary.

Seventh Embodiment

In this embodiment, as shown in FIG. 15, the film between wiring layers15, the film between wiring layers 23, and the film between via layers21 are respectively formed of the SiOCN film E. In this case, thedielectric constant is increased in comparison to the first and secondembodiments in which the film between wiring layers 15, the film betweenwiring layers 23, and the film between via layers 21 are respectivelyformed of the SiOC film C. However, the process is significantlysimplified in comparison to the fourth to sixth embodiments in which thefilm between wiring layers 15, the film between wiring layers 23, andthe film between via layers 21 are respectively comprised of a pluralityof films. In addition, since the composition of the SiOCN film E isclose to the SiCN film A in comparison to the SiOC film C, the reductionin adhesion at the interface with the SiCN film A, which constitutes thepart of the film between wiring layers 15, the film between wiringlayers 23, and the film between via layers 21, is not hardly caused.Note that it is desirable that the nitrogen concentration in the SiOCNfilm E is set to 10 atoms % or less in order to prevent the increase ofthe dielectric constant.

In the foregoing, the invention made by the inventors thereof has beenconcretely described based on the embodiments. However, it goes withoutsaying that the present invention is not limited to the foregoingembodiments and the various changes and modifications can be made withinthe scope of the present invention.

For example, in the fifth to seventh embodiments, it is also possible toform the stopper insulating films 14 and 22 and the cap insulating film20 with only the SiCN film or only the SiC film.

Also, in the first to seventh embodiments, the case where the film madeof low dielectric constant material is used to form the film betweenwiring layers and the film between via layers of the damascene copperwiring has been described. However, the present invention is not limitedto this. For example, the present invention can be applied to the casewhere the interlayer insulating film made of a low dielectric constantmaterial is formed on the wiring comprised of a refractory metal filmsuch as aluminum alloy or tungsten formed by the use of, for example,the lithography technique and the dry etching process.

The present invention is the technique effectively applied to thesemiconductor device including the copper wiring formed by the use ofthe damascene process and the interlayer insulating film with lowdielectric constant.

1-21. (canceled)
 22. A semiconductor device, comprising: a firstinsulating film formed over a semiconductor substrate and having a firstwiring trench; a first metal formed in the first wiring trench; a secondinsulating film formed over the first metal and over the firstinsulating film; a third insulating film formed over the secondinsulating film; a fourth insulating film formed over the thirdinsulating film and having a thickness greater than thicknesses of thesecond and third insulating films; a contact hole formed in the second,third and fourth insulating films; and a second metal formed in thecontact hole, wherein the first metal and the second metal are composedof copper as a main component, wherein the second insulating film iscomposed of a material including silicon, carbon and nitrogen, whereinthe third insulating film is composed of a material including siliconand carbon, wherein the fourth insulating film is composed of a materialincluding silicon, oxygen and carbon and has a dielectric constant lowerthan a dielectric constant of a silicon oxide film, wherein aconcentration of nitrogen in the second insulating film is higher than aconcentration of nitrogen in the third insulating film, and wherein anadhesion property of the third insulating film to the fourth insulatingfilm is larger than an adhesion property of the second insulating filmto the fourth insulating film.
 23. A semiconductor device according toclaim 22, wherein the first insulating film comprises a first film, asecond film formed over the first film, and a third film formed over thesecond film.
 24. A semiconductor device according to claim 23, whereinthe first film is composed of a material including silicon, oxide andcarbon, wherein the second film is composed of a material includingsilicon and carbon, and wherein the third film is composed of a materialincluding silicon, oxide and nitrogen.
 25. A semiconductor deviceaccording to claim 24, wherein an adhesion property of the second filmto the third film is larger than an adhesion property of the first filmto the third film.